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Effects of injection pressure variation on mixing in a cold supersonic combustor with kerosene fuel

  • Authors: Liu, Wei-Lai , Citation: Liu, W.L. et al. 2017. Effects of injection pressure variation on mixing in a cold supersonic combustor with kerosene fuel. , Zhu, Lin , Qi, Yin-Yin , Ge, Jia-Ru , Luo, Feng , Zou, Hao-Ran , Wei, Ming , Jen, Tien-Chien
  • Date: 2017
  • Subjects: Injection pressure , Transversal cavity injection , Cold supersonic flow
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/244204 , uj:25253
  • Description: Abstract: Spray jet in cold kerosene-fueled supersonic flow has been characterized under different injection pressures to assess the effects of the pressure variation on the mixing between incident shock wave and transverse cavity injection. Based on the real scramjet combustor, a detailed computational fluid dynamics model is developed. The injection pressures are specified as 0.5, 1.0, 2.0, 3.0 and 4.0 MPa, respectively, with the other constant operation parameters (such as the injection diameter, angle and velocity). A three dimensional Couple Level Set & Volume of Fluids approach incorporating an improved Kelvin-Helmholtz & Rayleigh-Taylor model is used to investigate the interaction between kerosene and supersonic air. The numerical simulations primarily concentrate on penetration depth, span expansion area, angle of shock wave and sauter mean diameter distribution of the kerosene droplets with/without evaporation. Validation has been implemented by comparing the calculated against the measured in literature with good qualitative agreement. Results show that the penetration depth, span-wise angle and expansion area of the transverse cavity jet are all increased with the injection pressure. However, when the injection pressure is further increased, the value in either penetration depth or expansion area increases appreciably. This study demonstrates the feasibility and effectiveness of the combination of Couple Level Set & Volume of Fluids approach and an improved Kelvin-Helmholtz & Rayleigh-Taylor model, in turn providing insights into scramjet design improvement.
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Tillage condition effects on soil/plow-breast flow interaction of a horizontally reversible plow

  • Authors: Luo, Feng , Zhu, Lin , Wei, Min , Zhang, Jia-Wen , Zhu, De-Quan , Jen, Tien-Chien
  • Date: 2019
  • Subjects: Flow interaction , Tool speed , Operational depth
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/406523 , uj:34182 , Citation: Luo, F., et al. 2019 : Tillage condition effects on soil/plow-breast flow interaction of a horizontally reversible plow.
  • Description: Abstract : The horizontally reversible plow (HRP) is commonly utilized because of higher performances than the regular mold-board plow. Soil/plow surface flow interaction during HRP tillage trends to incur so severe pressure on the plow-breast as to reduce the plow life. This paper numerically characterized the soil/plow-breast flow interaction and subsequently assessed tillage-condition effects on the plow-breast surface. These tillage conditions herein involved tool speed and operation-al depth. The simulations showed that for either tool speed or operational depth the maximum pressure appeared at the plow-shank of the plow-breast and that the soil pressures were increased with them. The computational fluid dynamics (CFD) based predictions qualitatively agreed with the preliminary experimental results at the identified settings with scanning electronic microscopy. Once again, CFD analysis is demonstrated to be feasible and effective enough to provide insight into improve the horizontally reversible plow by predicting real soil behaviors.
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Commuting tillage operations of HRP under hydraulic cylinder movements on plough-breast performance

Numerical investigation of a silicon six-wafer microcombustor under the effect of heat loss through the outer walls

Feasibility and effectiveness of heat pipe cooling in end milling operations : thermal, structural static, and dynamic analyses : a new approach

  • Authors: Zhu, Lin , Jen, Tien-Chien , Yen, Yi-Hsin , Kong, Xiao-Ling
  • Date: 2011
  • Subjects: Heat pipes , Heat pipe cooling
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/384755 , uj:5288 , http://hdl.handle.net/10210/14957
  • Description: In this paper, the feasibility and effectiveness of heat pipe cooling in end milling operations are investigated. A new embedded heat pipe technology was utilized to remove the heat generated at the tool-interface in end milling processes. Numerical studies involved four cases, including dry milling, fluid cooling, heat pipe cooling, and heat pipe cooling with cutting fluid supplied. The thermal, structural static, and dynamic characteristics of the endmill were investigated using a numerical calculation with fast finite element plus solvers based on explicit finite element analysis software. The results demonstrate that the heat pipe end-mill is most feasible and effective in the actual end milling processes
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Structural design of a silicon six-wafer micro-combustor under the effect of heat transfer boundary condition at the outer walls

  • Authors: Zhu, Lin , Jen, Tien-Chien , Zhu, Mei , Yin, Cheng-Long , Kong, Xiao-Ling
  • Date: 2010
  • Subjects: Micro-combustors , Heat transfer
  • Type: Article
  • Identifier: uj:5281 , http://hdl.handle.net/10210/14950
  • Description: The aim of this investigation was to establish a methodology for designing highly stressed micro fabricated structures by studying the structural design issues associated with a silicon six–wafer micro combustor under the effect of heat transfer boundary condition at the outer walls. Some experimental and numerical simulation results have indicated that the flame can not be sustained in the micro combustor if the poor heat transfer coefficients at the outer wall are present. This could cause the combustor wall temperature higher than the auto ignition temperature of reactants and results in the upstream burning. Since silicon has relatively poor high temperature strength and creep resistance when the temperature is above the brittle to ductile transition temperature (BDTT), e.g. 900K, the combustion in the recirculation jacket could possibly damage the micro combustor due to the high wall temperature.
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Experimental analyses to investigate the feasibility and effectiveness in using heat pipe-embedded drills

  • Authors: Zhu, Lin , Jen, Tien-Chien , Yin, Cheng-Long , Kong, Xiao-Ling , Yen, Yi-Hsin
  • Date: 2012
  • Subjects: Heat pipe cooling , Drilling , Heat pipes
  • Type: Article
  • Identifier: uj:5289 , http://hdl.handle.net/10210/14958
  • Description: This paper presents an experimental investigation to verify the feasibility and effectiveness of heat pipe cooling in drilling operations. The basic idea is to insert a heat pipe at the center of the drill tool with the evaporator close to the drill tip and the condenser at the end of the drill. Consequently, the heat generated at the tool–chip interface can be removed by convection heat transfer. Experimental studies were involved in three cases, including solid drill without coolant, solid drill with coolant, and heat pipe drill. Drilling tests were conducted on a CNC machining center with full immersion cutting. The cast iron square block was used as the workpiece, and the high-speed steel was chosen for the drill tool material. Flank wear is considered as the criterion for tool failure, and the wear was measured using a Hisomet II Toolmaker’s microscope. The tests were conducted until the drill was rejected when an average flank wear greater than 0.10 mm was recorded. The results demonstrate that using a heat pipe in the drilling process can effectively perform thermal management comparable to the flooding coolant cooling used pervasively in the manufacturing industry, extending the tool life of the drill.
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Numerical investigation of the structure of a silicon six-wafer micro-combustor under the effect of hydrogen/air ratio

  • Authors: Zhu, Lin , Jen, Tien-Chien , Ji, Ying-Feng , Yin, Cheng-Long , Zhu, Mei
  • Date: 2010
  • Subjects: Micro-combustors
  • Type: Article
  • Identifier: uj:5266 , http://hdl.handle.net/10210/14935
  • Description: Research reports indicate that sufficiently high equivalence ratio of the hydrogen/air mixture leads to the upstream burning in the recirculation jacket, possibly damaging the micro- combustor due to the high wall temperature. This work investigates the influences of the equivalence ratio of the mixture on the structure of a micro-combustor device. Numerical simulation approaches focused on the structural design of the micro-combustor with the flame burning in the recirculation jacket. Combustion characteristics of the combustor were first analysed based on 2D computational Fluid Dynamics (CFD), and then thermo-mechanical analysis on the combustor was carried out by means of 3D Finite Element Analysis (FEA) method. The results showed that the most dangerous locations where the critical failure could possibly occur lay at the burning areas in the recirculation jacket due to the poor bonding, the high temperature and the residual stress. The results of this study can be used for the design and improvement of the micro-combustors.
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Combined finite element and multi-body dynamics analysis of effects of hydraulic cylinder movement on ploughshare of horizontally reversible plough

  • Authors: Zhu, Lin , Peng, Shuang-Shuang , Cheng, Xi , Qi, Yin-Yin , Ge, Jia-Ru , Yin, Cheng-Long
  • Date: 2016
  • Subjects: Movement , Hydraulic cylinder (HC) , Share-point
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/213195 , uj:21117 , Citation: Zhu, L. et al. 2016. Combined finite element and multi-body dynamics analysis of effects of hydraulic cylinder movement on ploughshare of horizontally reversible plough.
  • Description: Abstract: Hydraulic Cylinder (HC), one of the key components of Horizontally Reversible Plough (HRP), takes the responsibilities for the commuting soiltillage of HRP. The dynamic behaviors of HC surely affectthe tilling performances of HRP. Based on our previously related work, this paper further addresses the effects of HC movements during tillage on ploughshare, especially at share-point, of HRP. For HC, uniform motion was considered in this study. A combined finite element and multi-body dynamics analysis (MDA) was implemented to assess both tillage kinematics and kinetics of the ploughshare. These numerical predictions were primarily involved in five different HC movement velocities and two actual HRP tilling scenarios, respectively, where loading data due to the HC movements were obtained from an MDA and applied to load a finite element modal of the ploughshare. Our results show that the importance of performing MDA as a preliminary step FEA to obtain an insight into the actual stress and strain variations at the share-point. Our findings demonstrate that the different movements of HC have no adverse effects on the service life of the ploughshare though they result in the maximum stress and strain at the sharepoint during HRP tillage.
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Numerical investigation of scale effect of various injection diameters on interaction in cold kerosene-fueled supersonic flow

  • Authors: Zhu, Lin , Qi, Yin-Yin , Liu, Wei-Lai , Xu, Bao-Jian , Ge, Jia-Ru , Xuan, Xiang-Chun , Jen, Tien-Chien
  • Date: 2016
  • Subjects: Scale effect , Transversal cavity injection , Cold supersonic flow
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/213203 , uj:21118 , Citation: Zhu, L. 2016. Numerical investigation of scale effect of various injection diameters on interaction in cold kerosene-fueled supersonic flow.
  • Description: Abstract: The incident shock wave generally has a strong effect on the transversal injection field in cold kerosene-fueled supersonic flow, possibly due to its affecting the interaction between incoming flow and fuel through various operation conditions. This study is to address scale effect of various injection diameters on the interaction between incident shock wave and transversal cavity injection in a cold kerosene-fueled scramjet combustor. The injection diameters are separately specified as from 0.5 to 1.5mm in 0.5mm increments when other performance parameters, including the injection angle, velocity and pressure drop are all constant. A combined three dimensional Couple Level Set & Volume of Fluids (CLSVOF) approach with an improved K-H & R-T model is used to characterize penetration height, span expansion area, angle of shock wave and sauter mean diameter (SMD) distribution of the kerosene droplets with/without considering evaporation. Our results show that the injection orifice surely has a great scale effect on the transversal injection field in cold kerosene-fueled supersonic flows. Our findings show that the penetration depth, span angle and span expansion area of the transverse cavity jet are increased with the injection diameter, and that the kerosene droplets are more prone to breakup and atomization at the outlet of the combustor for the orifice diameter of 1.5mm. The calculation predictions are compared against the reported experimental measurements and literatures with good qualitative agreement. The simulation results obtained in this study can provide the evidences for better understanding the underlying mechanism of kerosene atomization in cold supersonic flow and scramjet design improvement.
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Effects of spray angle variation on mixing in a cold supersonic combustor with kerosene fuel

  • Authors: Zhu, Lin , Luo, Feng , Qi, Yin-Yin , Wei, Min , Ge, Jia-Ru , Liu, Wei-Lai , Li, Guo-Li , Jen, Tien-Chien
  • Date: 2018
  • Subjects: Spray angle , Transversal cavity injection , Cold supersonic flow
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/270288 , uj:28726 , Citation: Zhu, L. et al. 2018. Effects of spray angle variation on mixing in a cold supersonic combustor with kerosene fuel. , Link to Published Version: https://doi.org/10.1016/j.actaastro.2017.12.013
  • Description: Abstract: Effective fuel injection and mixing is of particular importance for scramjet engines to be operated reliably because the fuel must be injected into high-speed crossflow and mixed with the supersonic air at an extremely short time-scale. This study numerically characterizes an injection jet under different spray angles in a cold kerosene-fueled supersonic flow and thus assesses the effects of the spray angle on the mixing between incident shock wave and transverse cavity injection. A detailed computational fluid dynamics model is developed in accordance with the real scramjet combustor. Next, the spray angles are designated as 45º, 90º, and 135º respectively with the other constant operational conditions (such as the injection diameter, velocity and pressure). Next, a combination of a three dimensional Couple Level Set & Volume of Fluids with an improved Kelvin-Helmholtz & Rayleigh-Taylor model is used to investigate the interaction between kerosene and supersonic air. The numerical predictions are focused on penetration depth, span expansion area, angle of shock wave and sauter mean diameter distribution of the kerosene droplets with or without evaporation. Finally, validation has been implemented by comparing the calculated to the measured in literature with good qualitative agreement. Results show that no matter whether the evaporation is considered, the penetration depth, span-wise angle and expansion area of the kerosene droplets are all increased with the spray angle, and most especially, that the size of the kerosene droplets is surely reduced with the spray angle increase. These calculations are beneficial to better understand the underlying atomization mechanism in the cold kerosene-fueled supersonic flow and hence provide insights into scramjet design improvement.
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